Rivers Continuing in Time

Billabong formation
How Billabongs Are Formed
A billabong is an isolated pond left behind after a river changes course. Diagram by Questacon.

A billabong ('bill-a-bong') is a body of water, like a large pond.

A billabong forms when a river changes its course, leaving a section cut off from the new river. When the river floods every wet season, the water in the billabong flows again as it connects up with the main river. Because of this the water stays fresh and supports an abundance of life.

Eventually the river breaks through the base of the loop and the extra bit that detaches forms a billabong. Billabongs can also be formed when a pool of water is left behind when flood or tidal waters recede.

The word billabong comes from the Wiradjuri ('weir-add-jeer-ee') language of south western New South Wales: bila meaning 'river' and bang meaning 'continuing in time or space'. Billabong is now in common use throughout Australia.